1. Field of the Invention
This invention relates to a power window controlling device for driving a window glass of motor vehicles and, more particularly to an improved device which is possible to reversely drive the window glass in the opening direction at the time when torque data of the driving motor of the window glass increases over the predetermined value while the window glass is traveling a predetermined distance in the closing direction. In the power window controlling device according to this invention, when the electric potential of the power source drops, the fall of potential is detected and the torque data of the electric motor is corrected according to the lowered electric potential.
2. Description of the Prior Art
As the power window controlling device for driving the window glass of the motor vehicle, a device is well known which has an electric motor of which armature shaft is operatively connected with the window glass through a window regulator. The armature shaft of the electric motor is secured with a rotation sensor to detect the rotation thereof. The rotation sensor is composed of a magnet attached on the armature shaft of the motor and a Hall element disposed around about the magnet. THe magnet is rotated together with the armature shaft, whereby a pulse-shaped detection signal (Hall voltage) is generated from the Hall element, therefore the number of revolutions (rotational speed) of the armature shaft is calculated by detecting pulse duration of the detection signal by the controller. Heretofore, the controlling device is known which is so designed as to prevent an obstruction to be caught between the window glass and the sash by recognizing the obstruction to be caught in accordance with lowering of the detected rotational speed of the electric motor and actuating the window glass in the reverse direction.
However, in the aforementioned power window controlling device the rotational speed of the electric motor is gradually lowered if the electric potential of the power source (battery) abruptly drops owing to actuation of the load such as lighting equipment and so, accordingly there is a problem in that there is the possibility that the controller may actuate the window glass in the reverse direction by misunderstanding the obstruction to be caught according to the lowering of the rotational speed of the electric motor.
This invention is made in view of the above-mentioned problem of the prior art, and it is an object to provide a power window controlling device which is not so easily misunderstand the obstruction to be caught even if the electric potential of the power source drops abruptly.
In order to accomplish the aforementioned object, the power window controlling device according to this invention is provided with a motor speed calculating means connected to the rotation sensor for calculating the rotational speed of the electric motor on basis of the rotation signal generated from the rotation signal generator of the rotation sensor and generating a rotational speed signal, a source voltage detecting circuit connected to the power source for detecting electric potential of the power source and converting the electric potential into a voltage signal, a data signal generating means connected to the source voltage detecting circuit for generating a correcting data signal obtained by including correction of time constant nearly equal to time constant TO of the electric motor to the voltage signal given by the source voltage detecting circuit, and a motor torque calculating means for calculating correcting data of torque of the electric motor according to the correcting data signal given by the data signal generating means and the rotational speed signal of the electric motor given by the motor speed calculating means, and for supplying a descending demand signal to the drive controlling means to lower the window glass at the time when the correcting data of the torque of the electric motor increases over a predetermined criterion value while the drive controlling means is supplying the ascending drive signal to the driving means in response to the ascending command signal generated from the CLOSE-switch.
In this invention, the electric potential of the power source is detected and converted into the voltage signal by the source voltage detecting means, the correcting data signal obtained by including correction of time constant nearly equal to time constant TO of the electric motor to the voltage signal given by the source voltage detecting circuit is generated by the data signal generating means, and the correcting data of torque of the electric motor is calculated by the motor torque calculating means according to the correcting data signal given by the voltage correcting means and the rotational speed signal of the electric motor given by the motor speed calculating means, and the descending demand signal is supplied to the drive controlling means to lower the window glass by the motor torque calculating means at the time when the correcting data of the torque of the electric motor increases over the predetermined criterion value. Namely, the correcting data of the torque of the motor is calculated in the case where the voltage of the power source changes, and the obstruction-caught state is detected by comparing the correcting data with the criterion value, therefore it is prevented to misunderstand the obstruction to be caught between the window glass and the sash.